The present invention relates to a double tube coupling used for connecting a double tube including an outer tube and an inner tube provided inside the outer tube.
A double tube includes an outer tube for circulating a first fluid. This coupling includes an inner tube provided inside the outer tube for circulating a second fluid. The inner tube extends outward from the end of the outer tube.
A double tube coupling includes a first joint for joining the outer tube and a first outside tube each other for guiding the first fluid. The coupling includes a second joint for joining the inner tube and a second outside tube each other by brazing for guiding the second fluid. The coupling includes a branched portion communicating with the first joint and having a hole for connecting the second joint from outside. The outer tube of the double tube is connected to the branched portion and the inner tube is inserted from the hole into the second joint.